Modulation of ovarian carcinoma OV632 antigen by interferons

OVAREX MAb-B43.13:IFN-gamma could improve the ovarian tumor cell sensitivity to CA125-specific allogenic cytotoxic T cells

Various immunological parameters were studied in 100 ovarian cancer patients injected with the OVAREX therapeutic vaccine (the functional component of which is anti-CA125 MAb-B43.13) to explain the serendipitous observation of prolonged survival after such treatment. In addition to CA125-specific humoral and cellular responses, interferon-gamma (IFN-gamma) was also found to be induced in those patients receiving the vaccine. In vitro studies indicated that the expression of MHC I, MHC II, and ICAM I in ovarian tumor cells were upregulated in response to IFN-gamma. Such tumor cells were also found to be more sensitive to CA125-specific cytotoxic T cells compared to cells that were not incubated with IFN-gamma.

Limited loss of nine tumor-associated surface antigenic determinants after tryptic cell dissociation

Disodium ethylenediaminetetraacetic acid (EDTA) or trypsin/EDTA are frequently used for the dispersion of monolayer cells into single cell suspensions allowing flow cytometric analysis of surface antigenic determinants. A disadvantage of EDTA is the slow action of this agent, whereas trypsin might affect the antigenic determinants under focus. We studied the possible deleterious effect of trypsin on three different ovarian carcinoma cell lines, COV413b, COV362.c14, and NIH:OVCAR-3, on cell surface antigenic determinants by flow cytometry. Either EDTA or trypsin/EDTA was used for detachment and dissociation of monolayer ovarian cancer cell lines, followed by indirect immunofluorescence with a panel of monoclonal antibodies directed against nine different surface antigenic determinants, including six markers directed against widely distributed antigens. Compared to EDTA, trypsin/EDTA resulted in higher total cell yields and rapid detachment and dissociation into single cell suspensions with significantly lower amounts of dead cells detected by both trypan blue and propidium iodide (PI). Large differences in antigen expression were observed for the different cell lines. However, all antigenic determinants tested could still be detected after tryptic proteolysis. Three antigenic determinants were significantly decreased after trypsin/EDTA compared to EDTA detachment. CA 125 was decreased on COV362.c14 and NIH: OVCAR-3 cells, respectively. BMA 180 and ICAM-1 were decreased on COV413b cells. This cell line-dependent decrease might be caused by differences in glycosylation. We conclude that trypsin/EDTA can be used for rapid monolayer cell detachment with high cell yields and limited loss of antigenic determinants tested.

Modulation of associated ovarian carcinoma antigens by 5 cytokines used as single agents or in combination

Optimization of intraperitoneal radioimmunotherapy of ovarian cancer depends on increasing the antigenic expression of tumor cells. For this purpose, we studied the effect of 5 cytokines (IFN-alpha, IFN-beta, IFN-gamma, TNF-alpha and TGF-beta), used as single agents or in combination, on 4 ovarian cancer cell lines which present different antigenic profiles with the monoclonal antibodies (MAbs) tested (OC125, OVTL-3, MOv 18 and MOv 19). Analyses were performed by flow cytometry and the Scatchard technique in order to study antigenic modulation. The effect on proliferation was determined by cell counting. Expression of O3 antigen, recognized by the OVTL3 MAb, was increased up to 2.5 times after IFNs and TNF-alpha (used as single agent) on the 2 lines presenting low basal expression (SHIN-3 and IGROVI). The expression of CA125 antigen and the antigens recognized by MOv 18 and MOv 19 MAbs was not increased by any of the cytokines tested. The combination IFN-gamma+TNF-alpha was synergistic on cytotoxicity and enhanced O3 expression, providing 10 times as many sites per cell on the SHIN-3 line. For 3 other associations (IFN-alpha+IFN-gamma, IFN-beta+IFN-gamma and IFN-alpha+TNF-alpha), there was an additive effect on O3 expression and on cell cytotoxicity.